Synthesis & Modeling Project
Richard A. Jahnke
Global synthesis of deep ocean carbon, carbonate, opal, and nutrient particle fluxes, benthic fluxes and sediment accumulation


PROJECT DESCRIPTION: We request support to synthesize sea floor flux and sediment composition measurements into a global description of biogenic fluxes in the deep ocean and sediments to provide the basis for testing models of organic matter fluxes. This work will be comprised of three specific activities.  
  1. Improve the fundamental data sets and compilations from which the estimated flux distributions and patterns are derived. This will include the incorporation of recent results (sedimentary organic C, CaCO3, opal, accumulation rates, and benthic fluxes of O2, TIC, nutrients, and selected tracers such as Ba and Ge) into the basic data sets; re-examination of the methods use to establish the mean sedimentary property fields; and expansion of the regions considered to include high latitude areas.

  2. Assimilate the individual measurements into a general Organic C - CaCO3 - Opal diagenetic model to provide a mechanistically more meaningful method for establishing basin-wide flux patterns.  

  3. Utilize the resulting flux distributions to test current models of particulate carbon fluxes in the ocean. For example, the importance of diatoms in determining POC fluxes can be assessed by comparing the ratio of silicate and organic carbon fluxes in the context of surface water productivity.

The development of an accurate understanding of global biogenic fluxes will require the synthesis of satellite, process, time-series and sea floor studies, each providing unique information. Sea floor studies, while not constraining temporal variability at the same time-scale as surface water processes, provide an assessment of the spatial distribution of deep fluxes not attainable by process and time-series studies and not visible by satellites. Sea floor studies further provide the link between ocean processes and the sediment record upon which paleoceanographic reconstructions depend. By providing improved quantitative descriptions of deep water column fluxes, benthic fluxes and sediment accumulation rates, this project will contribute to the following SMP objectives:

  • Synthesis of observations of particulate export production
  • The mechanisms and rates of mid- to deep-water particle flux and remineralizatio n as well as sediment diagenesis
  • Controls on the distributions of the production, transport, and remineralization of calcium carbonate and silica
  • Spatial extrapolation of estimates of biogeochemical fluxes (e.g. export production) from local to basin and global scales


DATA: Jahnke's seafloor oxygen flux data from the publication: Jahnke, Richard A. 1996. The global ocean flux of particulate organic carbon: Areal distribution and magnitude. Global Biogeochemical Cycles 10: 71-88. are now available as NetCDF.
PUBLICATIONS: - no publications listed -
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Richard A. Jahnke
Skidaway Institute of Oceanography
10 Ocean Science Circle
Savannah, Georgia 31411
tel: 912-598-2491
fax: 912-598-2310